We shall attempt to determine the biologic importance of a humoral immunosuppressive factor(s) found in cancer serum and cancer ascites in the pathogenesis of cancer. We shall isolate this suppressive factor from the protein present in the ascites of human cancer patients. We shall use the isolated macroglobulin factor to produce a radioimmunoassay for quantitative measurement of this factor, and for identification and determining relationship to other suppressive factors. This antisera will also be used for further purification using immunosorbent columns, and, potentially, for treatment of patients. We shall attempt to find antagonists for this factor, utilizing extracorporeal immunosorbent removal. We shall begin to use this substance to facilitate transplantation especially bone marrow transplants used for cancer treatments.